A Microsoft employee who tweeted about an unreleased Nokia Windows phone earlier this month has left the company after being told that he violated Microsoft's social-media policy, according to an All Things Digital report.

It started on September 7, when Joe Marini, who worked as a Seattle-based principal program manager on the Windows Phone team, tweeted: "I just got a chance to try out one of the slickest looking #Nokia phones I have ever seen. Soon, you will too!" The tweet contained a Windows Phone 7 hashtag, #WP7.

Via AllThingsD

Marini sent subsequent tweets about the device, including one that rated it an "8" and another that said "the camera was good, but I didn't have optimal lighting."

GeekWire broke the news today that Marini stepped down after being informed that he would be let go for violating Microsoft's social-media and blogging policy (PDF). The guidelines, which are not unusual for companies in this era of ubiquitous social networking, tell employees to "be smart" and to not disclose information in tweets or blog posts that would otherwise be considered confidential.

"We routinely do not discuss personnel matters, but I can confirm that Joe Marini no longer works at Microsoft," a Microsoft representative told AllThingsD.

This incident, of course, is not the first well-publicized case of an employee losing a job due to statements made on social-networking sites. Earlier this month, the National Labor Relations Board, a federal organization that safeguards employee rights, announced that five people who were fired from their jobs after posting complaints on Facebook about working conditions will now be able to return to their positions.